/*jslint todo: true */
"use strict"; //$NON-NLS-0$
// TODO Please see
// http://stackoverflow.com/questions/368280/javascript-hashmap-equivalent

// linking the key-value-pairs is optional
// if no argument is provided, linkItems === undefined, i.e. !== false
// --> linking will be enabled
function Map(linkItems) {
	this.current = undefined;
	this.size = 0;

	if (linkItems === false) {
		this.disableLinking();
	}
}

Map.noop = function() {
	return this;
};

Map.illegal = function() {
	throw new Error("illegal operation for maps without linking"); //$NON-NLS-0$
};

// map initialisation from existing object
// doesn't add inherited properties if not explicitly instructed to:
// omitting foreignKeys means foreignKeys === undefined, i.e. === false
// --> inherited properties won't be added
Map.from = function(obj, foreignKeys) {
	var map = new Map();

	for (var prop in obj) {
		if (foreignKeys || obj.hasOwnProperty(prop)) {
			map.put(prop, obj[prop]);
		}
	}

	return map;
};

Map.prototype.disableLinking = function() {
	this.link = Map.noop;
	this.unlink = Map.noop;
	this.disableLinking = Map.noop;
	this.next = Map.illegal;
	this.key = Map.illegal;
	this.value = Map.illegal;
	this.removeAll = Map.illegal;

	return this;
};

// overwrite in Map instance if necessary
Map.prototype.hash = function(value) {
	return (typeof value) + ' ' + (value instanceof Object ? (value.__hash || (value.__hash = ++arguments.callee.current)) : value.toString()); //$NON-NLS-0$
};

Map.prototype.hash.current = 0;

// --- mapping functions

Map.prototype.get = function(key) {
	var item = this[this.hash(key)];
	return item === undefined ? undefined : item.value;
};

Map.prototype.put = function(key, value) {
	var hash = this.hash(key);

	if (this[hash] === undefined) {
		var item = {
			key: key,
			value: value
		};
		this[hash] = item;

		this.link(item);
		++this.size;
	} else {
		this[hash].value = value;
	}

	return this;
};

Map.prototype.remove = function(key) {
	var hash = this.hash(key);
	var item = this[hash];

	if (item !== undefined) {
		--this.size;
		this.unlink(item);

		delete this[hash];
	}

	return this;
};

// only works if linked
Map.prototype.removeAll = function() {
	while (this.size) {
		this.remove(this.key());
	}
	return this;
};

// --- linked list helper functions

Map.prototype.link = function(item) {
	if (this.size === 0) {
		item.prev = item;
		item.next = item;
		this.current = item;
	} else {
		item.prev = this.current.prev;
		item.prev.next = item;
		item.next = this.current;
		this.current.prev = item;
	}
};

Map.prototype.unlink = function(item) {
	if (this.size === 0) {
		this.current = undefined;
	} else {
		item.prev.next = item.next;
		item.next.prev = item.prev;
		if (item === this.current) {
			this.current = item.next;
		}
	}
};

// --- iterator functions - only work if map is linked

Map.prototype.next = function() {
	this.current = this.current.next;
};

Map.prototype.key = function() {
	return this.current.key;
};

Map.prototype.value = function() {
	return this.current.value;
};
